Preheat the oven to 400 degrees. Lightly butter a large pie dish, place on a cookie sheet and set aside.

Dice the bacon and cook in a saute pan over
medium heat until lightly browned. Remove the bacon pieces from the pan
onto a towel-lined plate and let cool.

While the bacon is cooking, clean, dry and dice
the leek (white and light green parts only) and cook it in the bacon
drippings. (You only need about 2 tablespoons of the bacon drippings, so
if you have more than that in the pan, pour it off before cooking the
leeks.) When the leeks are just beginning to brown, scoop them out of
the pan and spread them evenly across the bottom of the pie dish.
Sprinkle the cooled bacon pieces over the leeks.

Snap the woody ends off of the asparagus spears
and chop the spears diagonally into 1/2-inch pieces. Spread the
asparagus pieces over the bacon and leeks. Grate the cheese and set
aside

Make the custard mixture: whisk together the
eggs, milk and cream thoroughly. Whisk in the salt, freshly-ground
pepper and nutmeg. Pour the egg mixture into the pie plate, sprinkle
with the cheese. Cook the egg custard until golden brown on top and just
firm in the center, about 30-40 minutes.